In conventional engines, engine combustion chamber valve opening and closing events are sequenced and driven by a cam shaft and conventional valve train components. Such valves are almost universally of the poppet-type. Such poppet valves are spring loaded toward a closed position and opened against the spring bias by a cam on a rotating cam shaft. The cam shaft is synchronized with the engine crankshaft to achieve valve opening and closing at preferred times in the engine cycle. This fixed timing is a compromise between the timing best suited for high engine speed and the timing best suited for lower speeds or engine idling speed.
Fuel for such engines is usually mixed with air, commonly in a carburetor, and provided to the cylinder through an intake valve or through a cam driven unit fuel injector. An example of a cam driven unit fuel injector is found in U.S. Pat. No. 4,527,738.
The prior art has recognized numerous advantages which might be achieved by replacing such cam actuated valve and unit injector arrangements with some other type mechanism for controlling the valve opening and closing events and the fuel injecting events as a function of engine speed as well as engine crankshaft position. Attempts to replace the cam for independently controlling the injection events of the unit fuel injector or the opening and closing events of an engine valve have included solenoids, colenoids, piezoelectric motors, voice coils, and high-force electromagnets. An exemplary unit fuel injector actuated by a piezoelectric motor is disclosed in U.S. Pat. No. 4,784,102. An exemplary engine valve actuated by a bi-stable electromechanical transducer is disclosed in U.S. Pat. No. 4,794,890.
However, no one has yet combined independently operable actuators into a system wherein a number of actuators are used to individually and independently control exhaust valves' opening and closing events, intake valves' opening and closing events, and unit fuel injector injection, and this is an object of the present invention.
Such an arrangement of independently operable "on-off" valve actuators, "on-off" valves, hydraulic fluid headers and rails, engine valves, and unit fuel injector provides an efficient and practical means for independently controlling the opening and closing events of the engine valves and the fuel injection of the unit fuel injector.